Quote:
Originally Posted by webrest
Why is the A/C in his 993 very efficient and the A/C in my '85 3.2 rubbish?
Any definite reasons why this is the case?
R.
Dave
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Sorry about the comparative post of an upgraded Carrera. I just wanted to bring WwEsT into the puzzle since his comments are always so helpful to the board.
The reason why the 964/993 system "
seems" to cool better is a mixture reliability improvements as well as condenser/evaporator and air flow improvements. The later model air cooled brought aluminum tubing in to replace the leaking plain rubber hose. A single condenser, twice as thick as the previous generation and powered by a rather large fan in terms of cfm. The evaporator increased in size. One evaporator blower became 2 blowers. Additional insulation, better venting. Put it all together and you have what "seems" to be better system. Seems in the eye of the beholder.
Now, the reality check. Is the 964/993 cheaper or less expensive long term, say maintenance wise, as compared to upgrading the previous generation 911 systems (prior to the introduction of the 964) ?
NOPE!
NOPE!
NOPE!
Compressors? SC/Carrera ... vs. 964/993, same cost, but I'd say I see more 964/993 failures then SC/Carrera
Refrigerant lines? the SC/Carrera models were all rubber, now upgraded with barrier hoses. The later 964/993 use primarily aluminum however there sections of rubber in the engine bay and by the front fender condenser. And, some of the 964/993 model lines have custom fittings you will not find easily. The 964/993 model are now needing their engine compartment rubber lines replaced (with barrier).
Drier? same cost, but the SC/Carrera is easier to replace.
Condenser? SC/Carrera models (deck lid and front) tend to hold up quite well, but to cool these cars down you need to add more. 964/993 models have 1 condenser and they are cost affordable, however its fan is proprietary and R&R time is 3 times as long. By the way, the Boxster/996 condensers are starting to leak.
Evaporators? SC/Carrera models up through 85 hold up well to a point, most need to be cleaned by now. 86-89 bonded a copper manifold to aluminum tubes (alike late 928 units), they all leak soon. The 964/993 models are all leaking! Yes, the 964/993 all need to be replaced. Time to R&R an SC/Carrera model is 45 mins for the experienced or 3 hours for the DIY. The model 964/993.... 12 to 15 hours! By the way, the Boxster/996 evaporators are starting to leak.
Controls? SC/Carrera model thermostat and fan speed switch are cheap and easy to replace. The 964/993 model AC control heads are very expensive to repair. The SC/Carrera heat vs. AC air piping or 'flaps' are cheap and seldom fail.
964/993 model fresh air/ ac air/ heated air mixing system is more complicated and timely to troubleshoot and need the hammer (reminiscent of the over designed 928).
Evaporator Blower Motor? SC/Carrera just use one and they hold up at least 20 years, rather easy to R&R. The 964/993 uses 2 unique proprietary blower/motors, costs are 3 times just for one motor and take 5 times longer to replace.
Bottom Line
We (our firm) hear's few complaints from 964/993 owners, however that is relative to the higher ratio of SC/Carrera on the road.
When we get a phone call from a client that "needs to convert to R134a", we know its because they have a leak in the system,
if its a 964/993 owner and the leak is the evaporator... they are shocked when they research the repair time.
The average upgrade time for SC/Carrera is ranges from 15 to 22 hours depending upon the range of upgrades,
while the time just to replace the evaporator in a 964/993 averages 15 hours.
There is more competition and selections of upgrades for the SC/Carrera, just read the boards,
however when a 964/993 owner in Tucson needs to cool down there are very few choices for upgrades.
Considering the number of SC/Carrera vs. the number of 964/993 on the road today,
and the number ratio of orders we receive for replacement AC parts or upgrades.....
I'd buy the SC/Carrera and upgrade. Less expensive in the long run and much easier for the DIY as well as having a shop do the work.
The 964/993 does have some appealing attributes, such as power steering, coil overs and few more ponies......
But my Carrera cabriolet, with its ice cold AC system, reliable motronic, simple component design, and.....
3.5 liter supercharged engine.. lol, leaves them all in the dust. Just IMO, .... lol.